Adsorption of 5-monocarboxyphenyl-10,15,20-triphenylporphyrin (MCTPP) to rutile TiO2(110) at room temperature produces molecules on the surface covalently anchored through the carboxylate group, coadsorbed with hydroxyl groups. At elevated temperatures, the free-base porphyrin molecules metalate on the surface, forming what we expect to be titanyl (TiO) porphyrin. The reaction is strongly coverage dependent with lower coverages metalating at lower temperatures, possibly caused by flat-lying molecules at low coverages being in closer proximity to the surface. This is in contrast to the behavior when exposed to Zn2+ ions in solution, where the coverage dependency is much less pronounced.

We have studied the adsorption and interfacial reactions of 2H-tetraphenylporphyrin (2HTPP) with cobalt-terminated Co 3 O 4 (111)a nd oxygen-terminated CoO(111)t hin films using synchrotron-radiation X-ray photoelectrons pectroscopy.A lready at 275 K, we find evidence for the formation of am etalateds pecies, most likely CoTPP,o nb oth surfaces. The degree of self-metalation increases with temperature on both surfaces until 475 K, where the metalation is almostc omplete. At 575 Kt he porphyrin coverage decreases drastically on the reducible cobalt-terminated Co 3 O 4 (111)surface, while highert emperatures are needed on the non-reducible oxygen-terminated CoO(111). The low temperature self-metalation is similar to that observed on MgO(100)s urfaces, but drastically different from that observed on TiO 2 (110), where no self-metalation is observeda tr oomt emperature. Figure 4. LEED diffraction patterns and Co 2p spectra of clean CoO(111)a nd Co 3 O 4 (111)a tr oom temperaturea nd of Co 3 O 4 (111)w ith adsorbed 2HTPP aftera nnealing to 675 K.Figure 5. N1 sX PS spectraa fter adsorption of 2HTPP on Co 3 O 4 (111)a nd on CoO(111)a t2 75 Ka nd on MgO (100) [13] and TiO 2 (110) [12] at room temperature.